export default function throttle(fn,time){
  let start=0
  return function(){
    let z1=new Date().getTime()//获取当前时间秒数
    let ars=arguments
    let tach=this 
    if(z1-start >time ){
      fn.call(tach,...ars)
      start= new Date().getTime()
    }
  }
}